lipids in living organisms

• what is a condensation reaction?

  A reaction between two molecules resulting in the formation of a larger molecule and the release of a water molecule
• What do we call the reaction that forms a triglyceride?

  esterification
• How would you break a triglyceride into its molecules?

  hydrolysis reaction
• • Hydrophobic – (scared of water) these molecules DO NOT form hydrogen bonds and so are repelled by water.
• • Hydrophilic – (Water loving) these form hydrogen bonds and so are attracted to water
• The non-polar tails are hydrophobic and are repelled by water. The phosphate heads are attracted to water and are hydrophilic.

  
• Properties:

  •Lipids store 3x more energy per gram than carbohydrates

  •Lipids can have hydrophobic and hydrophilic regions

  •Lipids can be fully non polar

  •Lipids are low density

  •Lipids can be found as liquids and solids at room temperature

  •Lipids are lighter than muscles
• Lipids act as Insulators:

  -They are part of myelin sheath providing insulation

  -They compose adipose tissue and act as insulation against heat loss

  -They can provide electrical insulation as a result of their non-polar properties.
• Lipids provide waterproofing:

  • This is due to the phospholipid hydrophobic and hydrophilic arrangement.
• Lipids provide Buoyancy:

  -The low density of fat tissue increases the ability of animals to float more easily
• Lipids allow for membrane formation and creation of hydrophobic barriers.
• Lipids have an important role in long term energy storage:

  -They are stored (mainly as triglycerides) under the skin and around vital organs

  -This can also provide cushioning to protect these organs
• Sterols are a type of lipid found in cells but they are not fats or oils. They contain four carbon rings with an OH group at one end and this gives them dual hydrophobic/hydrophilic properties like with phospholipids

  
• Cholesterol is a sterol:

  •It is positioned between phospholipids to increase cell membrane stability and regulate fluidity

  •It is also used to produce vitamin D, steroid hormones and bile